Carburetor inlet valve



H. A. CARLSON ET AL 3,086,750

CARBURETOR INLET VALVE A ril 23, 1963 Filed Feb. 2, 1961 F I 2 INVENTOR.

HAROLD A. CARLSON ALEX N. SZWARGULSKI ite State This invention relatesto carburetors for internal combustion engines, and particularly tofloat actuated needle valves for maintaining a predetermined constantfuel level within a fuel bowl.

Conventional float actuated needle valves for carburetors comprise avalve body having a metallic seat for engagement by the tapered end of ametallic needle. To prevent leakage and flooding of the carburetor, theneedle and seat must be manufactured to exact tolerances, and the fuelmust be free from particles of foreign material which might interferewith proper seating of the needle. Also, when carburetors of this typeare used on engines employed to drive boats, automobiles, and airplanes,engine vibration or rough travel of the vehicle may cause the float tooscillate and open the needle valve slightly when additional fuel is notrequired in the fuel bowl.

It is, therefore, an object of the invention to provide a novelcarburetor needle valve structure adapted to insure proper seating ofthe needle against the valve seat to prevent flooding of the carburetor.

Another object of the invention resides in the provision of a novelcarburetor needle valve, the operation of which is little affected byengine vibration or rough usuage.

A further object of the invention resides in the provision of a novelcarburetor needle valve structure during the operation of which theefiect of particles of dirt in the fuel is minimized in interfering withproper seating of the needle.

The invention embodies other novel features, details of construction andarrangement of parts which are hereinafter set forth in thespecification and claims, and illustrated in the accompanying drawing,forming part thereofwherein:

FIG. 1 is a side elevation in several partial sections, illustrating acarburetor provided with a float actuated needle valve embodyingfeatures of the invention.

FIG. 2 is an enlarged fragmentary longitudinal section showing theneedle valve structure of FIG. 1.

FIG. 3 is an enlarged view of one end of the needle valve of FIG. 2during a fabrication step thereof.

FIG. 4 is a transverse plan view of the needle structure of FIG. 2 withthe tip removed.

Referring now to the drawing for a better understand ing of theinvention, a downdraft carburetor is shown in FIG. 1 as comprising anair horn section 2, a main body section 3, and a throttle outlet section4, said sections being secured together and forming a mixture conduit 6having a stack of venturis 7, 7a and 7b in the main body section. Thecarburetor is mounted on the intake manifold M of a conventionalinternal combustion engine N adapted for use in driving a vehicle.

A choke valve 9, operable responsive to intake air flow, is rotatablymounted in an unbalanced manner on a valve shaft 10 in the air hornsection 2, which forms the air inlet end of the mixture conduit 6. Athrottle valve 8 is rotatably mounted on a shaft in the outlet end ofthe mixture conduit 6. Throttle shaft 15 is fixed to a throttle lever15a connected by means of a suitable linkage 15b to a manual control.

The main carburetor body section 3 is provided with a fuel bowl 12having a fuel inlet 13 provided with a screen filter 14 fixed within aninlet recess 13a. A fuel inlet valve 16, includes a needle valve 30having a tapered 3,086,756 Patented Apr. 23, 1963 point 34 in contactwith a valve seat of a valve body structure 36 to control fuel flow frominlet 13 into fuel bowl 12. A float 17 carries an arm 17a pivotallymounted at 18' within the fuel bowl to actuate the needle valve 31 formaintaining a substantially constant fuel level within the bowl 12. Fuelis supplied to the bowl from a fuel tank 15 by means of a conventionalengine-operated fuel pump 20 interposed in a fuel conduit 25 leading tothe fuel inlet 13.

A fuel metering orifice 19 leads from the fuel bowl 12 to an upwardlyinclined main fuel passage 21 having a main fuel nozzle 22 discharginginto the primary venturi 7. Fuel flow from bowl 12 through orifice 19into fuel passage 21 is controlled by a metering rod 40 having a steppedend 41 positioned in the metering orifice 19. Movement of rod 40 toposition a diiferent stepped portion in orifice 19 provides a change infuel flow through the orifice 19. An idle fuel system is shown ascomprising a fuel well 23 leading upwardly from the main fuel passage21. The well 23 has a metering tube 24 therein communicating with anidle passage 26 provided with idle ports 27 and 28. An idle adjustmentscrew 29 is provided for the idle port 28.

The fuel inlet valve 16 includes the needle 30 formed with a body 32 ofnon-circular cross section (FIG. 2 and FIG. 4). One end of the needle 30is formed with a conical tip 34. The other end of the needle 30 isformed with a rounded head 40 for engagement by the float arm 17a. Theneedle is mounted for reciprocable movement within a cylindrical bore 42formed in the valve body 36. The upper end of the valve body 36 isformed with external threads 44 (FIG. 1) for detachable engagementwithin a threaded aperture leading through a wall of the carburetor tothe inlet recess 13a.

The valve body 36 is formed with a second cylindrical bore 46 coaxiallyaligned with the bore 42 and of smaller diameter. The bore 46 forms ashoulder 38, with bore 42 to provide a valve seat for tip 34 of needle30.

The included angle of taper of the conical tip 34 of the needle 30 isfrom 60 to for seating engagement against the sharp circular edge 38 ofthe valve seat.

In operation, fuel is forced by pump 20 from the fuel source or fueltank 15 through fuel connections 25 into the inlet 13 of the carburetor.Fuel will flow through the screening 14 and the fuel passages 46 and 42past the needle valve 30, when the float structure 17 of the carburetoris in a downward position to release needle 30 from its fuel passageclosing position. When the fuel bowl 12 is filled to the desiredpredetermined level, the float lever 17a will force the needle valve 30against the valve seat 38 and close off further flow of fuel to thecarburetor. During engine operation, fuel fills the fuel passage 21 tothe same level as within the bowl. Air flow through the mixture conduit6 passes through the venturi stack 7-7a, causing a low pressure area atthe mouth of fuel nozzle 22. Atmospheric pressure on the fuel level inthe fuel bowl 12 forces fuel up the fuel passage 21 and out of thenozzle 22 to mix with the air in the mixture conduit 6. The flow of airand fuel mixture into the manifold M of the engine is controlled in awell known manner by the manually operated throttle valve 8.

As fuel flows from the fuel bowl 12 through the fuel passage 21 and thefuel nozzle 22, the level of fuel in bowl -12 is lowered, with aresulting lowering of the position of float 17. The downward movement offloat arm 17a permits the fuel valve 30 to drop downwardly under theforce of gravity and fuel pressure from above to permit fuel flow frominlet 13 into the fuel bowl 12 to replenish that used by the engine.

The tip 34 of the needle valve 30 is formed of a synthetic rubbermaterial, such as a fluoroelastomer compo- 3 sition which is notaffected by contact with fuel. The use of such a rubber-like materialprovides a more eflicient operation of the valve structure 36. The fuelflowing through the valve structure 36 often contains particles of dirtwhich can become lodged between the needle tip 34 and the valve seat 38.The presence of dirt between the valve and its seat tends to keep thevalve structure open, with the result that the fuel bowl 12 becomesflooded due to flow of fuel under pump pressure past the valve tip 34.Forming the valve tip of a rubber or resilient material will enable thetip to give and enclose the dirt particle and still provide asufliciently good seal to prevent flow of fuel through the valvestructure 36. g

It also is advantageous to provide a needle having a rubber tip whichwould adapt itself to all sizes of valve seats to which it might beapplied. For example, the inlet size of passage 46 varies somewhat fromcarburetor to carburetor, depending upon its size and the amount of fuelflow desired through the carburetor. However, the passage 42 may beretained at the same size irrespective of the designed size of passage46. In a like manner, then, the needle 30 which slidingly fits withinpassage 42 is retained at the same tize and it is desirable that therubber tip 34 be one which will operate successfully for all variationsin the size of passage 46. This has been difficult with a rubber tippedneedle due to the fact that if the passage 46 of the valve structure 36is a maximum, the valve seat 38 will meet the needle tip 34 at a pointadjacent to the region at which the rubber is fixed to the metal ofneedle 30 or near the lower edge of the rubber tip 34, as viewed in FIG.2, for example' At this point, the rubber is not as resilient as it isat an intermediate region between the upper end of tip 34 and the lowerregion at which it contacts the metal of the needle 30. Also, it hasbeen found that there is in this lower region of the tip 34 anunevenness or wrinkling where the rubber is fastened to the metal of theneedle. Accordingly, it is desirable that a larger rubber tip beutilized so that, as shown in FIG. 2, an intermediate region 'of the tip34 contacts the valve seat 38. In this region, then, the rubber of thetip is more resilient than at the lower surface of the tip. However, toprovide a needle of having a larger rubber tip, it has been necessary togo to a metal needle 30 of larger diameter, in order to providesuflicient area to attach the tip 34. This has encountered a costproblem in the construction and design of the carburetor, since a largerpassage 42 for the larger needle has been required with a resultingredesign of the valve structure 36. Thus, the difliculty has been thatof providing different valve structures for different sized carburetorsin order to provide room for a larger needle having a larger rubber tiIn accordance with the invention, however, a rubber tip needle for acarburetor is provided having a sufl'iciently large rubber tip which isadaptable to carburetor valve structures of varying sizes. FIG. 2discloses the rubber tip needle 34 of the invention fixed and anchoredto a metal shank 32 of the needle valve by forming in the metal shank acentral bore 50 and in the cylindrical end portion 52 a pair of annularrings or collars 54 and 56. The shank 32 as shown in FIG. 4 has atriangular crosssection forming longitudinal ribs 31 centering needle 30within bore 42. FIG. 3 shows a sectional view of the upper end of themetal shank '32 of the needle prior to its final formation. This figureshows the two annular collars or rings 54 and 56 formed substantiallycoaxial with the common axis of the needle and the central bore 50. Inorder that the structure may receive a larger rubber tip, in accordancewith the invention, the annular rings 54 and 56 are flared outwardly, asshown in the cross section of FIG. 2.

FIG. 4 shows a plan view of the upper end of the needle 32 after theflaring has taken place and before the rubber tip 34 has been added. Itcan be seen from this view of FIG. 4 that the lip of annular ring 54 nowextends outwardly a greater radial distance than its position in FIG. 3.However, it does not go as far as the greatest radial dimension of theneedle 30 which is limited by the diameter. of passage 42. As shown inFIG. 4, the flare of ring 54 is somewhere intermediate the originaldiameter of ring '54 and the outer extend of the rib portions 31 of theneedle 30. Thus, with the greater radial extent of flare of the upperend of ring 54, a larger tip 34 may be applied to the end of needle 30than is possible if the ring 54 were restrained to its originaldimension, as shown in FIG. 3.

In like manner, and in accordance with the invention, the second orinner annular ring 56 is also flared outwardly and in a direction towardthe outer ring 54. This is shown in a cross sectional view of FIG. 2,and provides between the rings 54 and 56 a space 58 which is partiallyenclosed by the flared upper end of the ring 56. This partially enclosedspace or annular region 58 is filled with the rubber of the tip 34 by amolding operation or by any other appropriate manner. The upper flaredend of the annular ring 56 locks the enclosed rubber in space 58 toprevent removal of the rubber tip from the needle 30.

As pointed out above, the metal needle 30 is made from metal rod stockhaving a triangular cross section, as shown in FIG. 4. The lib portions31 of the stock in one size of needle of the type described and usedsuccessfully, extend substantially .125 mill from the axis of the valveneedle 30. One end of the material is made or formed into thecylindrical end portion 52, having an outside diameter of mills. Endportion 52 is tangent to the sides of the needle. The annular collars 54and 56, as well as the annular region 58, may be formed in the end ofthe cylindrical portion 52 in any appropriate manner. In the specificneedles described, the annular collar 54 has an outside diameter ofmills while the inner annular collar 56 has an outside diameter of 92mills. The radial dimension of space 58 between the annular collars 54and 56 is of 47 mills. Bore 50 is one of 40 mills diameter and isdrilled with a depth of substantially of an inch, although this depth isnot a limiting dimension.

The two annular collars 54 and 56 are flared outwardly, by a sleeve anddie tool in which the sleeve is placed over the cylindrical end portion52 of the needle and has an inside diameter of the amount desired forthe outside diameter of the flared portion of collar 54. A tool then isinserted into the sleeve and has surfaces which contact the tops ofcollars 5'4 and 56 (FIG. 3) and which, upon applying sufficient amountof pressure to the tool, will cause the tops of the collars to be flaredoutwardly in the manner shown in FIGS. 2 and 4. This procedure is moreof a metal drawing operation which presses out the tops of the collarsand provides a conical surface to each.

The flaring procedure should be done so as to prevent undue stretchingof the metal of the two collars 54 and 56 which would cause breakage orcracking. This can be done with known procedures. However, it is also apart of this invention to provide certain fractures or cracks in theinner collar 56. These fractures are shown in FIGS. 2 and 4 andrepresented by reference numeral 62. The fractures 62 are easily formedsince the smaller diameter collar 56 will be stressed beyond its stresslimits. Design of tool will also assist the cracking. These cracks orfractures 62 of the inner ring are of a distinct advantage since, whenthe rubber tip 34 is molded onto the flared rings 54 and 56, the rubbernot only is pressed downwardly to fill the annular space 58 between thetwo rings, but is simultaneously forced into the fractures 62 to cause afurther locking of the rubber tip to the metal of the needle 30.

The dimensions given above for a specific needle are only illustrativeof a needle which has been used successfully in a manner described andin accordance with the invention. None of these dimensions areparticularly limiting and may be varied in any manner as seen fitwithout changing the invention. It has been found, however, that thedepth of the annular space 58 is somewhat critical since, if the metalof the rings 54 and 56 becomes too thin, the metal will tend to buckleand wrinkle at the base of rings 54 and 56 when pressure is applied bythe tool to the top portions of these rings to flare them outwardly.Thus, it is necessary that the metal thickness of the rings 54 and 56 besuch as to stand the pressures applied to form the flue of the tworings. The steel may be annealed, however, to prevent any fracturing orcracking of the metal when the flares are formed. As the flare is formedin the outer ring 54, the metal of the ring is forced outwardly andagainst the sleeve to form a true roundness of the outer ring 54. Thisis necessary to provide a corresponding roundness of the conical surfaceof the rubber tip 34. As the die forces the metal of ring 54 against thesleeve, there is a coining of the edge of ring 54 at this point. Thisprovides a smooth rim of the flare and permits the rubber of tip 54 toadhere closely to the metal of the needle 30.

The pair of flared annular rings 54 and 56 thus provide a means forfirmly anchoring the rubber of tip 34 to the needle 36. The flare of theinner ring 56 not only locks the rubber within the annular channel 58,but also forces the rubber adhering to the ring 54 tightly against theinner surface of the flared portion of ring 54 and prevents it fromseparating from the surface during curing operations of the rubber. Thedepth of the bore 59, as pointed out above, is not critical, however, itdoes provide a further means for anchoring the rubber tip within theshank portion of the needle 30. The particular construction of theflared annular rings is one which firmly anchors the rubber to the metalof the needle and prevents the pulling away of the rubber when theneedle is removed from the die after the rubber tip has been formed. Atthis time the rubber is only partially cured, and in the past there hasbeen a tendency of the partially cured rubber to be separated from themetal of the needle when removed from the die. The novel locking meansprovided by the annular flared rings minimizes this disadvantage. Uponfurther curing of the rubber, the needle is ready for use in acarburetor. The novel locking features of the rubber to the metal needleprovides a rubber tip fuel valve needle, which will not pull away fromthe metal during operation.

We claim:

1. A valve needle for a carburetor, having a valve seat in a fuelpassage, said needle comprising, a tip on one end of said valve needleadapted to abut said valve seat to close said fuel passage, said valveneedle having a pair of coaxial annular rings integral with andextending from said one needle end, the free end of one of said ringsbeing flared outwardly from the common axis thereof, said needle tipcomprising resilient fuel resistant material having a conical shape andanchored between said rings.

2. A valve needle for a carburetor, having a valve seat in a fuelpassage, said needle comprising, a tip on one end of said valve needleadapted to abut said valve seat to close said fuel passage, said valveneedle having a pair of coaxial annular rings integral with andextending from said one needle end, the free end of one of said ringsbeing flared outwardly from the common axis thereof, the other one ofsaid rings enclosing the flared end of said one ring, said needle tipcomprising resilient fuel resistant material having a conical shape andanchored between said rings.

3. A valve needle for a carburetor, having a valve seat in a fuelpassage, said needle comprising, a tip on one end of said valve needleadapted to abut said valve seat to close said fuel pasage, said valveneedle having a pair of coaxial annular rings integral with andextending from said one needle end, the free ends of said rings beingflared outwardly from the common axis thereof, one of said ringsenclosing the flared end of the other one of said rings, said needle tipcomprising resilient fuel resistant material having a conical shape andanchored between said flared rings.

4. A valve needle adapted to be mounted for movement within a fuelpassage having a valve seat, a tip on one end of said valve needleadapted to abut said valve seat to close said fuel passage, said valveneedle having a pair of flared annular rings integral With and extendingfrom said one needle end, said needle tip comprising resilient materialhaving a conical shape and anchored between said flared rings.

5. A valve needle adapted to be mounted for longitudinal movement withina fuel passage having a valve seat, a tip on one end of said valveneedle adapted to abut said valve seat to close said fuel passage, saidvalve needle having an annular collar integral with and extending fromsaid one needle end, the free end of said collar being flared outwardlyfrom the axis of said needle, said needle tip comprising resilientmaterial having a conical shape and enclosing said flared collar end andextending through said annular collar.

6. A valve needle adapted to be mounted for longitudinal movement withina fuel passage having a valve seat, a tip on one end of said valveneedle adapted to abut said valve seat to close said fuel passage, saidvalve needle having a pair of spaced coaxially formed collars integralwith and extending from said one needle end, the free end of the innerone of said collars being flared outwardly from the axis thereof, saidneedle tip comprising resilient material having a conical shape andfilling the space between said collars.

7. A valve needle adapted to be mounted for longitudinal movement withina fuel passage having a valve seat, a tip on one end of said valveneedle adapted to abut said valve seat to close said fuel passage, saidvalve needle having a pair of coaxial annular rings integral with andextending from said one needle end, the free end of one of said ringsbeing flared outwardly from the common axis thereof, said needle tipcomprising resilient fuel resistant material having a conical shape andanchored between said rings.

8. A valve needle adapted to be mounted Within a fuel passage having avalve seat, said valve needle including a valve body and a conical tipon one end thereof adapted to close said fuel passage, said valve bodyterminating at one end in a pair of integral spaced outwardly flaredaxially aligned annular ring portions defining outwardly open inner andouter sockets, said tip comprising resilient material formed with aconical terminal at one end with its other end extending into thesockets defined by said annular rings and anchored therein.

References Cited in the tile of this patent UNITED STATES PATENTS1,235,389 Skuttle July 31, 1917 1,422,054 Heide July 4, 1922 2,414,577Adair et a1. Jan. 21, 1947 2,521,314 Therolf Sept. 5, 1950 2,550,441Battling Apr. 24, 1951 2,752,937 Hieger July 3, 1956 FOREIGN PATENTS86,044 Denmark Apr. 7, 1936

1. A VALVE NEEDLE FOR A CARBURETOR, HAVING A VALVE SEAT IN A FUELPASSAGE, SAID NEEDLE COMPRISING, A TIP ON ONE END OF SAID VALVE NEEDLEADAPTED TO ABUT SAID VALVE SEAT TO CLOSE SAID FUEL PASSAGE, SAID VALVENEEDLE HAVING A PAIR OF COAXIAL ANNULAR RINGS INTEGRAL WITH ANDEXTENDING FROM SAID ONE NEEDLE END, THE FREE END OF ONE OF SAID RINGSBEING FLARED OUTWARDLY FROM THE COMMON AXIS THEREOF, SAID NEEDLE TIPCOMPRISING RESILIENT FUEL RESISTANT MATERIAL HAVING A CONICAL SHAPE ANDANCHORED BETWEEN SAID RINGS.